Gas turbine engines, such as those used to provide thrust to an aircraft, are internal combustion engines that use air as the working fluid. In general, gas turbine engines may include a fan section and a core engine located downstream of the fan section. In operation, air may be drawn into the engine and accelerated by the fan section, and a fraction of the indrawn air may be routed through the core engine where the air may be combusted with fuel to provide energy to drive the engine and provide forward thrust to an associated aircraft. In an upstream to downstream order, the core engine may include a compressor section, one or more combustors, a turbine section, and an exhaust nozzle.
The fan section, the compressor section, and the turbine section may each have one or more rotors with rotating airfoils (or blades). The rotor includes a disk having three main sections: 1) a rim supporting the airfoils, 2) a bore radially inboard of the rim, and 3) a web connecting the bore to the rim. In general, the rim may be positioned radially outward of the self-sustaining radius (SSR) of the rotor, while the bore may be positioned radially inward of the SSR. The SSR of the rotor is the radius with respect to the rotational axis of the rotor outside of which the rotor cannot control its own deflection, or sustain itself, under a given rotational loading. The bore may constrain and control stresses in rotor material positioned radially outward of the SSR (primarily the rim), and the web may transfer the bore's restraint to the rim.
Rotor disks in gas turbine engines are often formed from heavy materials, such as metal, and may require significant amounts of material and space to accomplish their structural requirements. The use of integrally bladed rotors (or IBRs), in which the blades are integrally formed with the disk, has led to reductions in part count and weight in some rotor systems. However, IBR designs may still require a disk of significant cross-section and mass, and may take up considerable space in the engine.
In an effort to produce lighter weight and higher strength rotor disks, some prior art systems have introduced reinforcing fibers and composite materials into rotor disks. For example, U.S. Pat. No. 7,811,062 describes the use of ceramic fibers embedded into the metallic material of the bore and the rim of a rotor disk. While effective, current fiber/composite-reinforced disk and IBR designs may be associated with several drawbacks. In particular, some designs may require complex manufacturing processes in which the reinforcing fibers are embedded or integrated into the metallic material of the disk during its manufacture. In addition, other designs may require mechanical fasteners to attach a composite reinforcement to the disk, thereby counteracting any weight reduction with the need for additional parts. Furthermore, it may be difficult to accommodate interfacial stresses between fiber/composite reinforcements and the metal material of the disk due to strength and thermal growth mismatches between metal and composite materials. Thus, there are numerous challenges and limitations with existing art that are to be overcome.
Clearly, there is a need for lighter weight and higher strength rotor disks that take up less space in gas turbine engines.